linux-kernel - Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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Date:   Wed, 11 Aug 2021 15:37:49 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Roja Rani Yarubandi <rojay@...eaurora.org>,
        Stephan Gerhold <stephan@...hold.net>
Subject: Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to
 set default perf state

On 11-08-21, 15:30, Rajendra Nayak wrote:
> In my case I don't want to error out if the property is missing, I want to error out
> only when the property exists but can't be translated into a performance state.
> 
> So currently I check if the property exists and *only then* try to translate it, Ulf asked
> me to skip the check. If I do that and I call of_get_required_opp_performance_state()
> unconditionally, and if it errors out I will need to put in additional logic (check for
> return value of ENODEV) to distinguish between the property-does-not-exist vs
> property-exists-but-cannot-be-translated case.
> It just seems more straight-forward to call this only when the property exists, Ulf?

The same check will be done by OPP core as well, so it is better to
optimize for the success case here. I will say, don't error out on
ENODEV, rest you know well.

-- 
viresh